A cathode ray tube is capable of producing considerable emanations outside the visible spectrum which emanations might be received and decoded at a distance in order to reproduce the information displayed on the screen of the cathode ray tube. One prior art technique for minimizing such emanations is disclosed in U.S. Pat. No. 2,673,342 granted on Mar. 23, 1954 to J. C. Sims, Jr. et al. and comprises a tapered body for shielding the major portion of the cathode ray tube. A metallic mesh screen is soldered to a plate which is then mounted within the large end of the tapered shield in order to permit viewing of the screen and yet minimize the emanation of signals within the nonvisual electromagnetic spectrum. It is also well known to coat the implosion screen of the CRT with a conductive material that is also transparent in order to suppress X-radiation. However, modern signal sensing and receiving apparatus is so sensitive that even these prior art techniques cannot prevent unauthorized receipt of information concerning the data displayed on the face of the CRT.
It is an object of the present invention to more fully enclose a cathode ray tube in order to minimize non-visual emanations therefrom.